1. Field of the Invention
The present invention relates to an apparatus for controlling a shared screen, wherein a plurality of conference participants share an application (sometimes abbreviated as “AP” in the following), which is executable from each communication terminal, to perform a conference via communication terminals connected to a network.
2. Description of the Prior Art
With the proceeding development of computer network systems in recent years, the progress of multimedia technology has promoted the dissemination of electronic conferences utilizing computer networks, so-called electronic conference systems and remote conference systems. Broadly classifying conventional configurations of electronic conference systems, there are the so-called “entire screen sharing” systems and “application sharing” systems.
In electronic conference systems based on entire screen sharing, one of the communication terminals connected to the network is selected as the terminal for providing the shared screen, and the display information for the entire display screen (window) of this communication terminal are sent to the other communication terminals over the network. Based on this display information for the shared screen, the other communication terminals display the shared screen on a portion of a display area of their own display devices. One such conventional conference system of the entire screen sharing type is for example the terminal apparatus for remote conferences in Publication of Unexamined Japanese Patent Application No. Sho 62-53084A.
In the other electronic conference system, the one of the application sharing type, there is no limitation to one specialized terminal as the server for the shared screen, communication terminals participating in the conference can provide applications running on their terminals as shared applications to other terminals over the network, windows of the shared applications are formed on a display screen of the communication terminals by starting the sharing of an application, and a plurality of windows of shared applications are displayed terminal display. Known electronic conference systems of this application sharing type include Microsoft's “Net Meeting™” and Intel's “ProShare™”.
However, the above-described electronic conference systems of the entire screen sharing type and the application sharing type pose the following problems.
First of all, in electronic conferences of the entire screen sharing type, a server communication terminals serving the shared screen provides its entire display screen as a shared screen to other client communication terminals, so that the server communication terminal cannot have its own local windows. Therefore, conference participants who use the communication terminal working as the shared screen server cannot open and use private applications. For all conference participants to use the shared screen and local windows for private applications, it is necessary to provide one extra communication terminal as a shared screen server terminal in addition to the communication terminals used by each conference participant.
In the electronic conference system of the entire screen sharing type, it is necessary to settle on a terminal as a shared screen server, or to decide on a communication terminal as a shared screen server from among the participant communication terminals before the electronic conference is held. If a terminal to provide a shared screen is settled on, the participant communication terminals have to connect to this terminal for providing a shared screen, the configuration of the network system is fixed and lacks flexibility, the resources distributed across the network cannot be utilized optimally, and the network costs tend to rise. If the communication terminal serving as the terminal providing the shared screen among the conference participants is decided on before holding the electronic conference, the resources on the network can be utilized efficiently, but negotiation and confirmation procedures among the conference participants are necessary before the conference, which is inconvenient, and does not always lead to an optimal distribution of network resources, when seen from the entire network.
Next, electronic conference systems of the application sharing type pose the problem of inconvenience. In electronic conference systems of the application sharing type, communication terminals participating in an electronic conference are on par to each other, provide private applications that can be performed on their terminal as shared applications open to other terminals, the windows for these shared applications can be displayed on display devices of these communication terminals, and all conference participants can have shared application windows and local windows. However, in an environment of multiple windows, where a plurality of windows are displayed on a display device, there is the problem that it is difficult to recognize whether an application displayed in a window is a shared application or not. Moreover, it is necessary to determine separately for each shared application, whether the participant providing the shared application accepts operation authority for that application to other participants or not, and as the number of shared application increases, their operation becomes complicated and burdensome.